wrote in
:

Stan, here in Canada, the forecast weather at your alternate must be
at least 300 feet and 1 mile above the approach minimums (or 600/2 or
800/2, whichever is higher). Supposedly to help ensure you can make
it in at your alternate. A kind of buffer.
I was just surprised to see that in the US, there are no such
additives.
And so, the alternate weather limits in the US can be the same as the
approach limits, in a very **FEW** cases.
CRQ was an example I found.
As an explanation to why it is only in a "few" cases, I notice in the
US that alternate weather limits must be at or above circling approach
limits too. And so, **normally** you find straight in approach limits
are less that alternate weather limits.
Canada does not have that circling minimums requirement as part of
alternate weather requirements.

In general, airports use standard alternate minimums, and the required
alternate minimums are listed on the back of the airport diagram. I must
confess that I really haven't read or worried about Part 91 alternate
minimums in a very long time, because I don't use them. My alternate
minimums are in my ops manual and ops specs. We add 200' to the
published approach minimum altitude for the approach we intend to use,
and use either 1 mile vis or published, whichever is higher, and only are
required to have 30 minutes reserve at the alternate. So for most
airports with an ILS, the alternate minimums are 400/1. As you can see,
there isn't a huge margin for error here. Fortunately, a diversion to
the alternate is rare, since we can cut the published visibility in half,
and since it's legal to descend to 100' above the TDZE with the approach
lights in sight, a miss off the ILS is seldom required, especially at
night, and I have never done one except on checkrides.

Flying a spam can for pleasure rather than profit is a very different
thing, though.

--
Regards,

Stan

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." B. Franklin